:root {
    --primary: #4361ee;
    --primary-dark: #3a56d4;
    --secondary: #7209b7;
    --success: #06d6a0;
    --danger: #ef476f;
    --light: #f8f9fa;
    --dark: #212529;
    --gray: #6c757d;
    --light-gray: #e9ecef;
    --border-radius: 12px;
    --box-shadow: 0 10px 20px rgba(0, 0, 0, 0.1);
    --transition: all 0.3s ease;
}

* {
    margin: 0;
    padding: 0;
    box-sizing: border-box;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background: linear-gradient(135deg, #f5f7fa 0%, #e4edf5 100%);
    color: var(--dark);
    min-height: 100vh;
    padding-bottom: 2rem;
}

.container {
    max-width: 1200px;
    margin: 0 auto;
    padding: 0 1.5rem;
}

/* 头部样式 */
header {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    padding: 1.5rem 0;
    box-shadow: 0 4px 12px rgba(0, 0, 0, 0.1);
    position: relative;
    overflow: hidden;
}

.header-content {
    display: flex;
    justify-content: space-between;
    align-items: center;
}

.logo {
    display: flex;
    align-items: center;
    gap: 1rem;
}

.logo-icon {
    font-size: 2.5rem;
    color: white;
}

.logo-text {
    font-size: 1.8rem;
    font-weight: 700;
}

.tagline {
    font-size: 1rem;
    opacity: 0.9;
    margin-top: 0.3rem;
}

.header-buttons {
    display: flex;
    gap: 1rem;
}

.btn {
    padding: 0.75rem 1.5rem;
    border-radius: var(--border-radius);
    font-weight: 600;
    cursor: pointer;
    transition: var(--transition);
    display: inline-flex;
    align-items: center;
    justify-content: center;
    gap: 0.5rem;
    text-decoration: none;
    border: none;
    font-size: 1rem;
}

.btn-primary {
    background-color: var(--primary);
    color: white;
}

.btn-primary:hover {
    background-color: var(--primary-dark);
    transform: translateY(-2px);
}

.btn-outline {
    background-color: transparent;
    border: 2px solid white;
    color: white;
}

.btn-outline:hover {
    background-color: rgba(255, 255, 255, 0.1);
}

/* 主内容区 */
.hero {
    text-align: center;
    padding: 4rem 0;
}

.hero h1 {
    font-size: 2.8rem;
    margin-bottom: 1.5rem;
    background: linear-gradient(90deg, var(--primary), var(--secondary));
    -webkit-background-clip: text;
    background-clip: text;
    color: transparent;
}

.hero p {
    font-size: 1.2rem;
    max-width: 700px;
    margin: 0 auto 2rem;
    color: var(--gray);
    line-height: 1.6;
}

/* 功能卡片 */
.features {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
    gap: 2rem;
    margin: 3rem 0;
}

.feature-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--box-shadow);
    transition: var(--transition);
    text-align: center;
}

.feature-card:hover {
    transform: translateY(-10px);
    box-shadow: 0 15px 30px rgba(0, 0, 0, 0.15);
}

.feature-icon {
    font-size: 3rem;
    color: var(--primary);
    margin-bottom: 1.5rem;
}

.feature-card h3 {
    font-size: 1.5rem;
    margin-bottom: 1rem;
    color: var(--dark);
}

.feature-card p {
    color: var(--gray);
    line-height: 1.6;
}

/* 上传区域 */
.upload-section {
    background: white;
    border-radius: var(--border-radius);
    padding: 3rem;
    box-shadow: var(--box-shadow);
    margin: 4rem 0;
    text-align: center;
}

.section-title {
    font-size: 1.8rem;
    margin-bottom: 1.5rem;
    color: var(--dark);
    text-align: center;
}

.upload-area {
    border: 3px dashed var(--light-gray);
    border-radius: var(--border-radius);
    padding: 3rem 2rem;
    margin: 2rem 0;
    cursor: pointer;
    transition: var(--transition);
}

.upload-area:hover {
    border-color: var(--primary);
    background-color: rgba(67, 97, 238, 0.03);
}

.upload-icon {
    font-size: 4rem;
    color: var(--primary);
    margin-bottom: 1.5rem;
}

.upload-text {
    font-size: 1.2rem;
    margin-bottom: 1rem;
    color: var(--gray);
}

.upload-hint {
    color: var(--gray);
    font-size: 0.9rem;
}

.upload-form {
    display: grid;
    grid-template-columns: 1fr 1fr;
    gap: 1.5rem;
    margin-top: 2rem;
}

.form-group {
    text-align: left;
}

.form-group label {
    display: block;
    margin-bottom: 0.5rem;
    font-weight: 600;
    color: var(--dark);
}

.form-control {
    width: 100%;
    padding: 0.75rem 1rem;
    border: 2px solid var(--light-gray);
    border-radius: var(--border-radius);
    font-size: 1rem;
    transition: var(--transition);
}

.form-control:focus {
    border-color: var(--primary);
    outline: none;
    box-shadow: 0 0 0 3px rgba(67, 97, 238, 0.2);
}

.btn-lg {
    padding: 1rem 2rem;
    font-size: 1.1rem;
    grid-column: span 2;
}

/* 下载区域 */
.download-section {
    background: white;
    border-radius: var(--border-radius);
    padding: 3rem;
    box-shadow: var(--box-shadow);
    margin: 4rem 0;
}

.download-form {
    display: flex;
    max-width: 600px;
    margin: 0 auto;
}

.download-input {
    flex: 1;
    padding: 0.9rem 1.5rem;
    border: 2px solid var(--light-gray);
    border-radius: var(--border-radius) 0 0 var(--border-radius);
    font-size: 1.1rem;
    transition: var(--transition);
}

.download-input:focus {
    border-color: var(--primary);
    outline: none;
}

.download-btn {
    padding: 0 2rem;
    border-radius: 0 var(--border-radius) var(--border-radius) 0;
    font-weight: 600;
    background-color: var(--primary);
    color: white;
    border: none;
    cursor: pointer;
    transition: var(--transition);
}

.download-btn:hover {
    background-color: var(--primary-dark);
}

/* 统计信息 */
.stats {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 1.5rem;
    margin: 4rem 0;
}

.stat-card {
    background: white;
    border-radius: var(--border-radius);
    padding: 2rem;
    box-shadow: var(--box-shadow);
    text-align: center;
}

.stat-value {
    font-size: 2.5rem;
    font-weight: 700;
    margin-bottom: 0.5rem;
    color: var(--primary);
}

.stat-label {
    font-size: 1.1rem;
    color: var(--gray);
}

/* 消息提示 */
.alert {
    padding: 1rem;
    border-radius: var(--border-radius);
    margin: 1rem 0;
    display: flex;
    align-items: center;
    gap: 1rem;
}

.alert-success {
    background-color: #d4edda;
    color: #155724;
    border: 1px solid #c3e6cb;
}

.alert-error {
    background-color: #f8d7da;
    color: #721c24;
    border: 1px solid #f5c6cb;
}

.alert-icon {
    font-size: 1.5rem;
}

/* 页脚 */
footer {
    background: linear-gradient(135deg, var(--primary) 0%, var(--secondary) 100%);
    color: white;
    padding: 3rem 0;
    margin-top: 4rem;
    border-radius: var(--border-radius);
}

.footer-content {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(250px, 1fr));
    gap: 2rem;
}

.footer-section h3 {
    font-size: 1.5rem;
    margin-bottom: 1.5rem;
    position: relative;
    padding-bottom: 0.5rem;
}

.footer-section h3::after {
    content: '';
    position: absolute;
    bottom: 0;
    left: 0;
    width: 50px;
    height: 3px;
    background: white;
    border-radius: 3px;
}

.footer-links {
    list-style: none;
}

.footer-links li {
    margin-bottom: 0.8rem;
}

.footer-links a {
    color: rgba(255, 255, 255, 0.8);
    text-decoration: none;
    transition: var(--transition);
    display: flex;
    align-items: center;
    gap: 0.5rem;
}

.footer-links a:hover {
    color: white;
    transform: translateX(5px);
}

.copyright {
    text-align: center;
    padding-top: 2rem;
    margin-top: 2rem;
    border-top: 1px solid rgba(255, 255, 255, 0.1);
    color: rgba(255, 255, 255, 0.7);
}

/* 响应式调整 */
@media (max-width: 768px) {
    .header-content {
        flex-direction: column;
        text-align: center;
        gap: 1rem;
    }
    
    .upload-form {
        grid-template-columns: 1fr;
    }
    
    .btn-lg {
        grid-column: span 1;
    }
    
    .hero h1 {
        font-size: 2.2rem;
    }
    
    .hero p {
        font-size: 1rem;
    }
}